(a) Field of the Invention
The present invention relates to an automatic transmission for a vehicle, and more particularly, to a planetary gear train of an automatic transmission for a vehicle capable of obtaining a power delivery performance improving effect and fuel consumption improving effect by implementing at least advance 11-speed shift-stages using minimal number of components and capable of decreasing driving noise using a driving point in a low revolution per minute (RPM) region of an engine.
(b) Description of the Related Art
In general, in an automatic transmission field, research has been conducted for achieving more shift-stages to maximize enhancement of fuel consumption and drivability of a vehicle, and recently, the increase of oil price is triggering a competition in enhancing fuel consumption of a vehicle. In particular, research for an engine has been conducted to achieve weight reduction and to enhance fuel consumption by downsizing and research for an automatic transmission has been conducted to simultaneously provide improved drivability and fuel consumption by achieving more shift-stages.
However, for the automatic transmission, as the number of shift stages increases, the number of internal parts, particularly, the number of planetary gear sets also increases and a full length of the transmission is thus increased, thereby causing mountability, production cost, weight, power transfer efficiency, etc., to be deteriorated. Therefore, it may be important for the automatic transmission to develop a planetary gear train capable of generating maximum efficiency using a minimal number of parts to increase a fuel consumption improvement effect through the achievement of the more shift-stages.
In terms of this, recently, the automatic transmission has been configured to implement a shift of 8-speed or more and has been installed within the vehicle, and research and development for a planetary gear train capable of implementing shift-stages of 8-speed shift-stages or more have been actively demanded. However, a general automatic transmission of 8-speed or more generally includes 3 to 4 planetary gear sets and 5 to 6 control elements (friction elements), and in this case, since the full length of the transmission is increased, there is a disadvantage that mountability is deteriorated.
Therefore, to achieve the more shift-stages of the automatic transmission, recently, a double row structure in which the planetary gear set is disposed on the planetary gear set has been adopted, or a dog clutch has been applied instead of a wet control element. However, an applicable structure is limited and deterioration of shift sense is accompanied due to the application of the dog clutch.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.